Adapter for automatic rivet guns



July 19, 1955 E, E. DUMAS ADAPTER FOR AUTOMATIC RIVET GUNS Filed Oct. 22, 1955 INVENTCR dzrardlfiams J (1. kimgfij United rates Patent ADAPTER FOR AUTOMATIC RIVET GUNS Edward E. Dumas, Haw River, N. C., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application October 22, 1953, Serial No. 387,664

4 Claims. (Cl. 218-47) This invention pertains to adapters for attachment to rivet guns and more particularly to a rivet gun head or adapter for engaging and pulling an enlarged portion of a mandrel that is mounted in a tubular rivet.

Many rivet guns that are used to pull a mandrel into a tubular rivet have relatively short, fixed stroke lengths and are not capable of setting a variety ofadifierent sized rivets. Frequently this type of rivet gun is unsuitable for gripping mandrels having an enlarged portion thereon.

Therefore the objects of this invention are to provide a rivet gun head adapted to .engage an enlarged portion of the mandrel of a tubular rivet assembly, and to set the rivet in a work piece by pulling the mandrel into the rivet by a succession of strokes of a number variable in accordance with the length of the mandrel to be pulled.

The above objects are achieved in the illustrated embodiment of this invention by providing a rivet gun head or adapter comprising a stationary sleeve vfor abutting a preformedhead of a tubular rivet, and a reciprocable arm slidable within the stationary sleeve. The sleeve is attached to a stationary portion of a rivet gun and the arm :7

is connected to a reciprocable pull rod of the rivet ,gun. The sleeve and the arm are provided with alignable longitudinally extending slots for passage therethrough of the rivet mandrel. The reciprocable arm is further provided with axially spaced first and second bifurcated shoulders engageable with an enlarged portion of the rivet mandrel whereby the mandrel after being engaged by the first shoulder may, by actuation of the reciprocable arm, be successively partially advanced for a predetermined distance into the rivet, engaged by the second shoulder and thereby completely pulled into the hollow rivet to expand the rivet into a tight engagement with a work piece.

Other novel features and advantages of the present invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, wherein:

Fig. 1 shows the adapter attached to a rivet gun and placed in operating position with respect to a work piece; Fig. 2 is a perspective View of the reciprocable arm;

Fig. 3 is an enlarged and partially cross sectional view I of the adapter taken on line 3-3 of Fig. 1 showing the reciprocable arm in a rest position, and, in full line, a rivet mandrel in position prior to actuation of the reciprocable arm, and in dotted lines, a rivet mandrel in position after completion of the first pulling step;

Fig. 4 is a view similar to Fig. 3 but shows the reciprocable arm in a retracted position and, in full line, a rivet mandrel after the first pulling step, and in dotted line, a rivet mandrel in the final or set position after the second pulling step;

Fig. 5 shows, partly in cross section, a portion of the adapter and a rivet assembly and illustrates, in dotted lines, a rivet mandrel in a flexed position immediately prior to engagement with the second bifurcated shoulder and, in full lines, the mandrel after engagement with the shoulder;

Z,7l3,439 Federated July 1.9, 1955 Fig. 6 is a cross sectional view of the adapter taken on line 6-6 of Fig. 3 and shows the mandrel in engagement with the first bifurcated shoulder prior to the first pulling step; and

Fig. 7 is a cross sectional view of the adapter taken .on line 7-7 of Fig. 3 and shows, in dotted lines, the mandrel in engagement with the second bifurcated shoulder after the first pulling step.

Referring now to the drawings and more particularly to Fig. 3, a work piece is shown comprising parts 12 and 13 which are to be riveted together. A rivet assembly comprises a tubular rivet 14 having a preformed head' portion 15 and a shank portion 16 and, mounted in the bore of the rivet 14, a mandrel indicated generally by the numeral 17 and having enlarged end portions 18 and 19, and a shaft composed of a smaller diameter portion 20 and a larger diameter portion 22. The work piece is provided with rivet holes 23 through which the rivet .assembly is inserted.

An adapter or rivet gun head, the subject of the present invention, is shown in which a stationary sleeve is indicated generally by the numeral 24 and comprises an upper portion'25 attachable by suitable means as by threads (not shown) to a stationary portion of a rivet gun 26 (Fig. l) and .a lower portion 27 threadedlyengageable with the upper portion and rigidly positioned with respect thereto by means of a lock nut 28. The rivet gun is of anysuitable type, such as a pneumatically operatedgun supplied with compressed air through conduit 21 (Fig. 1

Lower portion 27 of the adapter is provided with axially extending slots 29 and 30 and radially extending slot 32.

A reciprocable arm indicated generally by the numeral 33 is slidably mounted within the sleeve 24 and comprises an upper member-.34 engageable at one extremity by suitable means to areciprocable pull rod 35 of the rivet gun 2,6, and at the other extremity to a lower member 36. Lower member 36 of the reciprocable arm 33 is provided with axial slots 37 and38 and radial slot 39, slots 37 and 39 registering, in the assembled portion, with slots 29 and 32, respectively, of sleeve 24 for passage therethrough of the mandrel 17, and slot 38 coacting with slot 30 .of sleeve 24 to provide for ejection of a broken portion of mandrel 17 after the setting operation. Lower member 36 of the reciprocable arm is provided with a first bifurcated shoulder 40 and axially aligned therewith a second bifurcated shoulder 42 having inclined surfaces 43.

In operation, the rivet gun head is loaded by passing the mandrel 17 through the opening defined by the aligned pairs of slots 29-37 and 39- 32 and engaging the large end portion 18 of the mandrel with the first bifurcated shoulder 40. The rivet assembly is then inserted into apertures 23 in the positioned work pieces. Alternately, the rivet assembly may be first positioned in the apertures in the work pieces and the rivet gun head then engaged with the projecting mandrel 17 in the operating position. The lower portion 27 of the sleeve 24 is in contact with the preformed head 15 of the rivet 14 and with the work piece 12. The reciprocable arm 33 is then retracted within the sleeve 24 by actuation, through compressed air of the attached pull rod 35 of the rivet gun 26, thereby pulling the mandrel 17 into the tubular rivet 14 to the position indicated in full lines in Fig. 4. The leverage for the pulling operation is obtained by simultaneously applying the pulling force to the enlarged end portion 18 of the mandrel and the force of reaction of the pulling force axially through the sleeve 24 while pushing the tool against the rivet head 15. The supply of compressed air is then cut off permitting return of pull member 36. During return of the reciprocable arm 33 to the rest position (Fig. 3) the tool is forcibly held against the rivet and in axial alignment therewith, whereby the enlarged head portion 18 of the mandrel 17 is slidably contacted by the inclined surfaces 43 of the second bifurcated shoulder 42. This results in a bending of the mandrel 17 through an angle within the elastic limit of the mandrel (Fig. Continued downward movement of the reciprocable arm 33 to the rest position results in a snapping of the enlarged head portion 18 of the mandrel 17 into engagement with the second bifurcated shoulder 42 as shown in dotted lines in Fig. 3. Upon a second upward movement of reciprocable arm 33 shoulder 42 pulls the mandrel 17 into its final or set position as shown in dotted lines in Fig. 4. At this position the enlarged head portion 19 of the mandrel 17, by engagement with the shank portion 16 of the rivet 14, forms a head 44 (Fig. 4) on the rivet 14, thereby rigidly securing together the work pieces 12 and 13.

Subsequent to the rivet setting operation, the mandrel 17 may be broken at the junction of parts 20 and 22 and all or a portion of the mandrel removed from the rivet if desired.

Obviously the present invention is not limited to a two-step pulling operation. The reciprocable arm could conceivably be provided with any desirable number of mandrel engaging bifurcations depending upon the length of mandrel to be pulled.

Other modifications of the present invention could be made without departing from the spirit and scope thereof.

What is claimed is:

1. An adapter for engaging an enlarged portion of a mandrel and pulling said mandrel into a tubular rivet to set said rivet in a work piece comprising a stationary sleeve for abutting the rivet, said sleeve having an aperture for admitting the mandrel into the sleeve, a reciprocable arm slidably mounted in said sleeve and having an aperture alignable with the aperture in the sleeve, and a plurality of axially-spaced bifurcated shoulders attached to the reciprocable arm for sequentially engaging and pulling the enlarged portion of the mandrel into the rivet thereby setting said rivet in the work piece.

2. A rivet gun adapter for pulling a mandrel in a tubular rivet comprising a stationary sleeve mounted on a rivet gun and adapted to apply the force of reaction of the pull to the rivet, a reciprocable arm actuated by the rivet gun and slidably mounted in the stationary sleeve, said stationary sleeve and said reciprocable arm each being provided with an aperture for passage therethrough of the mandrel, a first bifurcated projection attached to the reciprocable arm, and a second bifurcated projection attached to the arm and having an inclined surface axially spaced from and facing toward the first bifurcated projection, said first and second bifurcated projections being engageable with an enlarged end of the mandrel and adapted to pull the mandrel into the rivet on first and second pull strokes of the reciprocable arm.

3. An adapter in combination with a rivet gun having power actuated means for pulling an enlarged headed mandrel into a tubular rivet said adapter comprising a slotted stationary sleeve for abutting the rivet, a reciprocable arm slidably mounted in the sleeve and operated by said power actuated means, said arm having a slot registering with the slot in the sleeve for admission therethrough of the mandrel, a first bifurcated shoulder on the reciprocable arm for engaging the head of the mandrel during a first pull stroke of the arm, a second bifurcated shoulder located on the reciprocable arm and axially spaced from and aligned with the first shoulder, said second shoulder being adapted to engage the head of the mandrel during a second pull stroke of the arm, and means for guiding the head of the mandrel from the first shoulder to the second shoulder in the interval between the first and second pull strokes.

4. In a power-operated rivet gun having a reciprocable pull rod adapted to pull a mandrel into a tubular rivet, a removable head comprising a stationary sleeve attached to the rivet gun and adaptable to apply the reactionary force of the pulling operation to the rivet, a partially hollow reciprocable arm attached to the pull rod of the rivet gun and slidably mounted in the sleeve, said sleeve and said arm being provided with mutually registering slots for passage therethrough of the mandrel, a plurality of axially aligned bifurcated shoulders formed on the inner surface of the reciprocable arm for engaging and pulling the mandrel into the rivet on alternate or pull strokes of the arm, inclined, bifurcated, planar surfaces connecting the shoulders whereby the partially pulled mandrel is guided into engagement with successive shoulders on alternate or return strokes of the arm until the mandrel is pulled completely into the rivet.

References Cited in the file of this patent UNITED STATES PATENTS 2,582,417 Croessant Jan. 15, 1952 

